As is commonly known, plate-fin heat exchangers such as a water-cooled charge air coolers (WCAC) can be used in a motor vehicle to cool air that has been compressed by a turbocharger or a supercharger prior to entering an engine of the vehicle. Typically, the plate-fin heat exchangers include a heat exchange core having a plurality of plates interposed with a plurality of fins. The plates form passages for receiving a coolant from a coolant circuit of the motor vehicle. As the compressed air flows through the heat exchanger, heat is transferred between the compressed air and the coolant.
In certain situations, undesired air may also be inadvertently introduced in the passages formed by the plates. For example, when coolant is introduced to the heat exchanger during a servicing or maintenance of the heat exchanger, undesired air may begin to accumulate and become trapped in the passages formed by the plates. The accumulation of the air minimizes the efficiency and performance of the heat exchanger.
To solve the problem of trapped air in the passages formed by the plates of the heat exchanger, the heat exchanger may include a bleed screw or bleed valve disposed at a coolant outlet spout of the heat exchanger to purge the air from the passages. However, in heat exchangers with plates including passages having multiple parallel pass configurations such as four, six, eight, or ten pass configurations, for example, the bleed screw or bleed valve disposed at the coolant outlet spout is ineffective in purging the air from all the passes of the passages. As a result, the heat exchanger performance and efficiency is adversely affected.
It would therefore be desirable to provide a plate-fin heat exchanger with plates that form a degas flow path that effectively convey and purge undesired air from all passages of the heat exchanger in order to maximize performance and efficiency thereof.